Don't try to overwrite an existing file if the contents are identical

[ocaisa]

No description provided.

[hattom]

Note that file permissions are not compared as part of filecmp.cmp:

> ls -althr file?
-rwxr-xr-x 1 thay grp-tok-ipp 12 Aug 13 13:15 file1
-rw-r--r-- 1 thay grp-tok-ipp 12 Aug 13 13:15 file2
> cat test_cmp.py 
#!/usr/bin/env python3
import filecmp
print(filecmp.cmp("file1", "file2"))
> python test_cmp.py 
True

Could this cause problems?

[boegel]

Note that file permissions are not compared as part of filecmp.cmp:

> ls -althr file?
-rwxr-xr-x 1 thay grp-tok-ipp 12 Aug 13 13:15 file1
-rw-r--r-- 1 thay grp-tok-ipp 12 Aug 13 13:15 file2
> cat test_cmp.py 
#!/usr/bin/env python3
import filecmp
print(filecmp.cmp("file1", "file2"))
> python test_cmp.py 
True

Could this cause problems?

This is a very good point imho, could result in unintended side effects/breakage?

[boegel]

At the very least we should also check whether file permissions are the same as well before skipping the actual copy operation?

[akesandgren]

Note that the permissions may have been changed later on by postinstallcmds or hooks or the normal EB change-permission step and thus permission differences should not be considered if the content is actually the same.

[ocaisa]

Closing this in favour of #4642 which I think is the real problem